/*
 * Copyright (C) 2006, 2007, 2008, 2013 Apple Inc. All rights reserved.
 * Copyright (C) Research In Motion Limited 2011. All rights reserved.
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 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
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#ifndef SKY_ENGINE_PLATFORM_FONTS_GLYPHPAGE_H_
#define SKY_ENGINE_PLATFORM_FONTS_GLYPHPAGE_H_

#include <string.h>
#include "flutter/sky/engine/platform/PlatformExport.h"
#include "flutter/sky/engine/platform/fonts/CustomFontData.h"
#include "flutter/sky/engine/platform/fonts/Glyph.h"
#include "flutter/sky/engine/wtf/PassRefPtr.h"
#include "flutter/sky/engine/wtf/RefCounted.h"
#include "flutter/sky/engine/wtf/RefPtr.h"
#include "flutter/sky/engine/wtf/unicode/Unicode.h"

namespace blink {

class SimpleFontData;
class GlyphPageTreeNode;

// Holds the glyph index and the corresponding SimpleFontData information for a
// given character.
struct GlyphData {
  GlyphData(Glyph g = 0, const SimpleFontData* f = 0) : glyph(g), fontData(f) {}
  Glyph glyph;
  const SimpleFontData* fontData;
};

// A GlyphPage contains a fixed-size set of GlyphData mappings for a contiguous
// range of characters in the Unicode code space. GlyphPages are indexed
// starting from 0 and incrementing for each 256 glyphs.
//
// One page may actually include glyphs from other fonts if the characters are
// missing in the primary font. It is owned by exactly one GlyphPageTreeNode,
// although multiple nodes may reference it as their "page" if they are supposed
// to be overriding the parent's node, but provide no additional information.
class PLATFORM_EXPORT GlyphPage : public RefCounted<GlyphPage> {
 public:
  static PassRefPtr<GlyphPage> createForMixedFontData(
      GlyphPageTreeNode* owner) {
    void* slot = fastMalloc(sizeof(GlyphPage) +
                            sizeof(SimpleFontData*) * GlyphPage::size);
    return adoptRef(new (slot) GlyphPage(owner));
  }

  static PassRefPtr<GlyphPage> createForSingleFontData(
      GlyphPageTreeNode* owner,
      const SimpleFontData* fontData) {
    ASSERT(fontData);
    return adoptRef(new GlyphPage(owner, fontData));
  }

  PassRefPtr<GlyphPage> createCopiedSystemFallbackPage(
      GlyphPageTreeNode* owner) const {
    RefPtr<GlyphPage> page = GlyphPage::createForMixedFontData(owner);
    memcpy(page->m_glyphs, m_glyphs, sizeof(m_glyphs));
    if (hasPerGlyphFontData())
      memcpy(page->m_perGlyphFontData, m_perGlyphFontData,
             sizeof(SimpleFontData*) * GlyphPage::size);
    else {
      for (size_t i = 0; i < GlyphPage::size; ++i) {
        page->m_perGlyphFontData[i] = m_glyphs[i] ? m_fontDataForAllGlyphs : 0;
      }
    }
    page->m_customFontToLoad = m_customFontToLoad;
    return page.release();
  }

  ~GlyphPage() {}

  static const unsigned char sizeBits = 8;
  static const size_t size =
      (1 << GlyphPage::sizeBits);  // Covers Latin-1 in a single page.
  static unsigned indexForCharacter(UChar32 c) { return c & 0xFF; }

  ALWAYS_INLINE GlyphData glyphDataForCharacter(UChar32 c) const {
    unsigned index = indexForCharacter(c);
    if (const CustomFontData* customData = customFontToLoadAt(index))
      customData->beginLoadIfNeeded();
    return glyphDataForIndex(index);
  }

  ALWAYS_INLINE GlyphData glyphDataForIndex(unsigned index) const {
    ASSERT_WITH_SECURITY_IMPLICATION(index < size);
    Glyph glyph = m_glyphs[index];
    if (hasPerGlyphFontData())
      return GlyphData(glyph, m_perGlyphFontData[index]);
    return GlyphData(glyph, glyph ? m_fontDataForAllGlyphs : 0);
  }

  ALWAYS_INLINE Glyph glyphForCharacter(UChar32 c) const {
    return glyphAt(indexForCharacter(c));
  }

  ALWAYS_INLINE Glyph glyphAt(unsigned index) const {
    ASSERT_WITH_SECURITY_IMPLICATION(index < size);
    return m_glyphs[index];
  }

  void setGlyphDataForCharacter(UChar32 c, Glyph g, const SimpleFontData* f) {
    setGlyphDataForIndex(indexForCharacter(c), g, f);
  }

  void setGlyphDataForIndex(unsigned index,
                            Glyph glyph,
                            const SimpleFontData* fontData) {
    ASSERT_WITH_SECURITY_IMPLICATION(index < size);
    m_glyphs[index] = glyph;
    setCustomFontToLoad(index, 0);

    if (hasPerGlyphFontData()) {
      m_perGlyphFontData[index] = fontData;
    } else {
      // A single-font GlyphPage already assigned m_fontDataForAllGlyphs in the
      // constructor.
      ASSERT(!glyph || fontData == m_fontDataForAllGlyphs);
    }
  }

  void setGlyphDataForIndex(unsigned index, const GlyphData& glyphData) {
    setGlyphDataForIndex(index, glyphData.glyph, glyphData.fontData);
  }

  const CustomFontData* customFontToLoadAt(unsigned index) const {
    ASSERT_WITH_SECURITY_IMPLICATION(index < size);
    return m_customFontToLoad ? m_customFontToLoad->at(index) : 0;
  }

  void setCustomFontToLoad(unsigned index,
                           const CustomFontData* customFontToLoad) {
    if (!m_customFontToLoad) {
      if (!customFontToLoad)
        return;
      m_customFontToLoad = CustomDataPage::create();
    }
    ASSERT_WITH_SECURITY_IMPLICATION(index < size);
    m_customFontToLoad->set(index, customFontToLoad);
  }

  void removeFontDataFromSystemFallbackPage(const SimpleFontData* fontData) {
    // This method should only be called on the system fallback page, which is
    // never single-font.
    ASSERT(hasPerGlyphFontData());
    for (size_t i = 0; i < size; ++i) {
      if (m_perGlyphFontData[i] == fontData) {
        m_glyphs[i] = 0;
        m_perGlyphFontData[i] = 0;
      }
    }
  }

  GlyphPageTreeNode* owner() const { return m_owner; }

 private:
  explicit GlyphPage(GlyphPageTreeNode* owner,
                     const SimpleFontData* fontDataForAllGlyphs = 0)
      : m_fontDataForAllGlyphs(fontDataForAllGlyphs), m_owner(owner) {
    memset(m_glyphs, 0, sizeof(m_glyphs));
    if (hasPerGlyphFontData())
      memset(m_perGlyphFontData, 0, sizeof(SimpleFontData*) * GlyphPage::size);
  }

  bool hasPerGlyphFontData() const { return !m_fontDataForAllGlyphs; }

  class CustomDataPage : public RefCounted<CustomDataPage> {
   public:
    static RefPtr<CustomDataPage> create() {
      return adoptRef(new CustomDataPage());
    }
    const CustomFontData* at(size_t index) const { return m_customData[index]; }
    void set(size_t index, const CustomFontData* data) {
      m_customData[index] = data;
    }

   private:
    CustomDataPage() { memset(m_customData, 0, sizeof(m_customData)); }
    const CustomFontData* m_customData[size];
  };

  const SimpleFontData* m_fontDataForAllGlyphs;
  GlyphPageTreeNode* m_owner;
  RefPtr<CustomDataPage> m_customFontToLoad;
  Glyph m_glyphs[size];

  // NOTE: This array has (GlyphPage::size) elements if m_fontDataForAllGlyphs
  // is null.
  const SimpleFontData* m_perGlyphFontData[0];
};

}  // namespace blink

#endif  // SKY_ENGINE_PLATFORM_FONTS_GLYPHPAGE_H_
